The present invention relates to metal salts of certain hydroxyaromatic compounds and methods of their preparation.
Metal salts of organic acidic materials have found extensive use in lubricant and fuel applications. A particularly prominence has been obtained by overbased salts, that is, salts which have been formed with an excess of base (often present as the carbonate). These materials serve as detergents in motor oil lubricants. Neutral and overbased salts have been prepared with a variety of metals and a variety of anions, including carboxylate, sulfonate, phenate, and others. However, formation of metal phenates has generally proved difficult, particularly with certain metals such as magnesium. In difficult cases only partial neutralization is possible without taking extreme measures. The present invention provides certain phenolic salts which are easy to prepare as substantially fully neutralized or even overbased materials.
U.S. Pat. No. 2,647,873, Matthews et al, Aug.4, 1953, discloses a lubricating composition containing a reaction product of an aromatic compound containing a polar radical, represented by the general formula R.sub.m --Ar--R'.sub.m --(X).sub.q, and an aldehyde such as formaldehyde, simultaneously reacted with a basic metallic compound such as calcium hydroxide. The reaction is generally carried out at a temperature ranging from about 50.degree. C. to about 150.degree. C. The product is subjected to a heat treatment.
U.S. Pat. No. 2,736,701, Neff, Feb. 28, 1956, discloses a lubricating oil composition which contains an oil-soluble complex obtained by heating an oil solution of a metal salt of a hydrocarbon substituted phenol-aldehyde condensation product and adding a basic metal inorganic compound. An example is the calcium salt of the tert-octylphenol-formaldehyde resin.
U.S. Pat. No. 3,425,989, Shepard et al., Feb. 4, 1969, discloses a process for producing phenol-aldehyde condensates, comprising heating a mixture of a phenol with an inorganic alkali catalyst, then introducing an aqueous solution of an aldehyde.
U.S. Pat. No. 3,793,201, Karn, Feb. 19, 1974, discloses a solution of oil-soluble basic magnesium salts of at least one organic acid and oil-soluble polyvalent metal salts of bridged phenols such as an alkylated phenol-formaldehyde condensation product of a sulfurized aliphatic hydrocarbon-substituted phenol.
U.S. Pat. No. 4,147,643, Pindar et al., Apr. 3, 1979, discloses additive compositions made by reacting (A) an aromatic compound having an OH or SH group, e.g. an alkyl substituted phenol; (B) an aldehyde; (C) a non-amino hydrogen, active hydrogen compound capable of forming Mannich bases (e.g., phenols); and optionally (D) an aliphatic alkylating agent. Sulfurized composition are made by sulfurizing the above compositions with elemental sulfur. The aromatic compounds of (A) can include linked poly-ring aromatic nuclei such as ##STR1## The compositions of this reference were believed to contain bridges derived from the organic residue of the aldehyde (B) linking the organic residues of the aromatic compound (A) and the active hydrogen compound (C). Thus, when (B) is formaldehyde, methylene bridges are formed. Additives such as ash-producing detergents may also be present.
U.S. Pat. No. 4,769,501, Iwahara, Sep. 6, 1988, discloses a process for producing an alkylphenol comprising reacting a phenol with an aldehyde and hydrogen in the presence of a catalyst such as an alkaline earth metal hydroxide.